Final comment.! Added in case this helps anyone in a similar position, although YMMV.

Re-reading my initial question in msg#1.. reallocating that space over 2TB with WD Disk Wizard did recover a lost partition. However because of bad advice (WD support said that would zero fill the whole drive), it wasn't tried initially,

HDD failure is guaranteed inevitable ! But not in a fairly new drive for no apparent logical reason - or instantly. Usually there's some warning... but I don't want to debate that, I just offer my findings if it helps anyone in the same boat.

HDD failure is guaranteed inevitable ! But not in a fairly new drive for no apparent logical reason - or instantly. Usually there's some warning... but I don't want to debate that, I just offer my findings if it helps anyone in the same boat.

Google did big study into hard drive failure rates, believe the outcome was that they would fail early on, or only after years and years of abuse.

I don't think there's anything "wrong" with it and any replacement would be no better (and re-furbished). They've given me a link to a diagnostic programme.. Drive is still in Win7 machine and everything copied from it. Depends what happens back in XP with the diagnostics. Suppose a reformat removes any lingering issues with all the mucking about....

Perhaps I should repeat the whole scenario and see if the same thing happens twice ?